Process of treating lead-carbonate ores



imams.

APPLICATION FILED SEPT. 30, 1919.

N. C. CHRISTENSEN. PROCESS 0F TREATlNG LEAD cARBoNATf- 035s.

Patented Sept. 13, 1 921.

lead in solution.

NIELS C. CHRISTENSEN, 01E' SALT LAKE CITY, UTAH.

ROCESS OF TBEATING LEAD-GARBGNATE GRES.

Leeds.

Specification of Letters Itatent. Patntd Sept, liga' QL Application 'lled september ilo, i919. Serial No. 327,403.

To all when@ -z'J may Concern:

Be it known that l, Nisils C. (.Hrzis'rzmssn, s citizen of `the United States` residingy :1t Salt Lake City, in the county ot' Salt Lahe und Stute of Utah. have invented eertain ne and useful improvements .in Processes of rreating Leadarloonute Gres, of which the following is a specieation.

- rllhis invention relates to the treatment ol carbonate ores of lead for the recovery ot the lead therefrom. My process is applicable to ell urbonzite ores which do not rontain too 4much soluble material Suchos lime stone. The process' hydrometallurgicul but the product may he treated by pyroinetallurgical methods if desired.

My process consists in treating the comininuted ore with a veoncentrated lsodium ehlorid solution containing iron salt-s in so lution. Either the sulfate or rhlorid may he used and either ferrous or ferritsalts.

l have -found that a strong salt solution con taining iron Salts arts on the earhonate of lead and brings it into solution and precipitates the iron in the iorrn ot' the hydroxid as indicated below:

The cold solution acts slowly and holds but a comparatively small percentage ot' lead. The hot solution :iets very rapidly and holds a eoinparatively large amount ot' Only :i very slight excess of iron salts over that theoretirally required to set on the lend carbonate is necessary. in the hot solution practically no excess being' necessary. A largel excess of iron salts should be avoided as thu amount of leed ohlorid which the sollitionovill hold is reduced hy the iron salts present. Sultates also reduce the solubility of the lead chlorid.

ln the aerompanying dievvingl is shown s. diagram illustrative oi the solubility of the leed chlorid at 'aiying temperzrtures.A

*leed in solution, lig-ming the density o' the solution as l, fi. e. it is theweigh't oi' leed in rentigrams held in one cubic centimeter of the solution.A This curve shows the great difference in the amount of lead chlorid held in the saturated solution when hot and when cold.

ln my preferred method of precipitating the lea( chloridl take advantage of this large dference iin the amount ot lead held' in the saturated solution het and cold to recover the lead from the solution.7 by treating the ore with just enough of the hot solution to set-ure a concentrated lead solution, sepa rating this hot lead solution from the ore and coolingit and 'separating the precipitated lead ehlorid from the cold solution.

My pret'eirecl method of precipitating the metallic lead trom the chlorid is an important step in the process es by it I regenerste the irorr salts necessary 'in the process.

This precipitation is secured by electrolyz ing the solution containing the leed with iron :modes o'r by treating the precipitated lead chlorid with metallicviron. ln either case ferrous ehlorid is formedand is used in dissolvinga more lead carbonate es indi' a ted below The electrolysis of the lead solution is very simple. the leed being' precipitated in the form of a sponge and the ferrous chlorid being formed at the snode.

`Cold solutions give good results but with warm or hot solutions a lower voltage and higher current density may he used. The roltagfeused may be reduced to less than .3 in a hot solution und current .densities as high us l0() amperes per square foot may be used with the concentrated lead solutions.

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Metallic iron does not precipitate the lead 'from the concentrated salt solution very readily so incase the lead chlorid is reduced h y direct treatment with iron the leafd rhlorid lpreeipitateal by cooling the hot solution is treated with the iron. rlhis is done by mixingthe ehlorid with water and bringing into Contact with the iron, enough water being used so that the ferrous chlorid solu tion does not become too concentrated.

The leed may also be precipitated from the salt solution by the addition of lime but' this method does not lend itsel'l to the regeneration ot ,the iron salts.

From the foregoing; itis readily seen that my complete process consists in treating the ore with a concentrated. salt solution con- 

